Technical Field
The present invention relates to a liquid ejection head.
Related Art
For example, a liquid ejection printing device that ejects liquid such as ink which can be printed on a printing medium is known. Among such liquid ejection printing devices, there is a liquid ejection printing device including an ink jet head employing a so-called ink jet system. The ink jet head is provided with a piezoelectric actuator in which plural long grooves are formed as pressure chambers which are filled with ink. Electrodes are formed on both side walls of each pressure chamber. When a predetermined driving pulse is applied to the electrodes, the side walls are deformed and a volume in the pressure chamber increases. Accordingly, a negative pressure causing ink to flow into the pressure chamber from a manifold is generated. When the application of the driving pulse is stopped, the volume of the pressure chamber is returned to the original volume. Accordingly, a positive pressure is generated in the pressure chamber and ink is ejected from a nozzle.
In the ink jet head, gray scales of printing using a multi-drop system are adjusted. The multi-drop system is a system in which ink is successively ejected to the same point. In the multi-drop system, ink successively ejected to each point may be one continuous ink droplet. According to the multi-drop system, since an amount of ink droplets impacted on each point can be adjusted, gray scales can be expressed on a printing medium.
For example, JP 2000-280463 A describes a driving method of an ink ejection device in which when a time required for a pressure wave to propagate in one way in an ink channel is defined as T, a wave width of a first ejection pulse signal which is initially applied is set to 0.35 T to 0.65 T and a wave width of a second ejection pulse signal or an ejection pulse signal applied subsequent thereto is set to almost T.